Thermoplastic Material
Thermoplaste | A service provided by |
|---|
|
| Polymer Service GmbH Merseburg |
| Tel.: +49 3461 30889-50 E-Mail: info@psm-merseburg.de Web: https://www.psm-merseburg.de |
| Our further education offers: https://www.psm-merseburg.de/weiterbildung |
| PSM on Wikipedia: https://de.wikipedia.org/wiki/Polymer Service Merseburg |
Thermoplastic material
Definition
Thermoplastic materials, also known as thermoplastics or plastomers, are a subgroup of plastics that can theoretically be melted down and cooled in a new form as often as desired. The ability to thermoplastically deform, melt and reshape is closely related to the recyclability of these materials. A key feature is that they can be deformed or melted under the influence of heat and can be reshaped using thermoplastic moulding processes. As a result of these properties, thermoplastic materials can usually also be welded and bonded, which means that there is a high degree of variability in the joining processes for these materials.
Classification of thermoplastics
Thermoplastics are mainly classified as so-called mass plastics, although the term high-temperature-resistant plastics (PTFE or PCTFE) is also used for various plastics, and when reinforced with organic or inorganic fibres (GF, CF, MF, NF), they are referred to as engineering or high-performance plastics. Thermoplastics usually consist of linear or branched macromolecules that are connected to each other by comparatively weak physical bonding forces, e.g. van der Waals forces. Depending on the type of these plastics, amorphous or semi-crystalline, the properties of these materials are characterised by viscoelastic and viscoplastic, i.e. time-dependent deformation behaviour. At the same time, this results in a wide range of properties, ranging from brittle to ductile or tough material properties. Chemical modification produces so-called copolymers, or polymer blends produced by mixing, which have characteristics that differ from the basic monomers, e.g. high toughness properties.
Macroscopic properties
The macroscopic energy-elastic properties are characterised, for example, by low to high tensile strengths and moduli of elasticity, very low (PMMA, PS) to very high (PP, PA) tensile strain at break, and low (PC, PP) to very high (ABS, PE) impact strengths. Classification is often based on tensile strain at break, which can be up to 100 % for these materials and, depending on the test temperature and test velocity, can often be significantly higher than this limit value. These plastics often react to mechanical or mechanical-thermal stresses with crazing and subsequent crack initiation as well as brittle failure (see also: component failure) in the case of brittle material behaviour, or with high plastic deformation in the case of ductile material behaviour. The manufacturing processes often result in high internal stresses and orientations, which manifest themselves in anisotropic properties.
Manufacture of thermoplastics
The most important thermoplastics used in technology are amorphous plastics, which only have a short-range order, such as PMMA, PS, PVC, PC, ABS or PPE, and semi-crystalline polymers with a long-range order, such as PP, PE, PA, PET, PBT or POM, all of which can be present as copolymers or blends if they are chemically or physically compatible and can also be filled or reinforced.
Thermoplastics are usually produced using polymerisation, polyaddition or polycondensation processes, whereby the polymer chains are formed by repeating basic monomers. The manufacturing processes for plastic components made of thermoplastics today range from injection moulding, injection compression moulding, compression moulding and extrusion to calendering, blow moulding, vacuum thermoforming and film blowing. These plastics can be machined mechanically by sawing, milling, planing, grinding and turning, and can be joined to form complex components by welding and bonding.
See also
- Fibre-reinforced plastics
- Layer silicate-reinforced polymers
- Thermosets
- Bio-plastics
- Material & Werkstoff
References
| [1] | Grellmann, W., Seidler, S. (Eds.): Mechanical and Thermomechanical Properties of Polymers. Landoldt Börnstein. Volume VIII/6A2, Springer, Berlin (2014) (ISBN 978-3-642-55166-6; see AMK-Library under A 16) |
| [2] | Elsner, P., Eyerer, P., Hirth, T. (Hrsg.): Domininghaus – Kunststoffe, Eigenschaften und Anwendungen. Springer, Berlin (2012) 8. Edition, (ISBN 978-3-446-44350-1; see AMK-Library under G 41) |
| [3] | Ehrenstein, G. W.: Polymerwerkstoffe – Struktur – Eigenschaften – Anwendung. Carl Hanser, Munich (2011) 3rd Edition (ISBN 978-3-446-42283-4; see AMK-Library under G 91) |